High pressure fail-safe gate-operating apparatus



Oct. 24, 1967 K. F. LEMLEY 3,348,378

HIGH PRESSURE FAIL-SAFE GATE-OPERATING APPARATUS Filed April 25, 1966INVENTOR. AfW/VfT/v F. LE'MLEV ATTORNEKfi United States Patent 3,348,378HIGH PRESSURE FAIL-SAFE GATE-OPERATING APPARATUS Kenneth F. Lemley, 144Woodhaven Lane, Pittsburgh, Pa. 15237 Filed Apr. 25, 1966, Ser. No.544,987 9 Claims. (Cl. 60-57) a reservoir immediately will be connectedwith the cylinder to close the gate. That system has proved to be verysatisfactory, but when the gate-operating cylinder is quite large thecompressed air tank or reservoir has to be made much larger than desiredand occupies too much space. This is because the air in the reservoir isat the same relatively low pressure as that delivered by the compressorwhich normally operates the gate, and therefore there has to be a largevolume of this compressed air stored in the reservoir to ensure closingof the gate. 7 It is among the objects 'of this invention to provideapparatus similar to that shown in my Patent 3,225,544, which canutilize a small compressed air reservoir for operating a largegate-operating cylinder, which requires no additional power except aninsignificant amount of electricity for closing a valve, and which isentirely automatic.

In accordance with this invention, a-reservoir contains compressed airthat is used only for closing agate in emergencies. There is a source ofcompressed air for Keeping the reservoir charged. Likewise connected tothe reservoir is a pressure intensifier that increases the air pressurein the reservoir above the pressure supplied by the source justmentioned. This intensifier includes a cylinder containing a piston foroperating the intensifier. A pair of conduits are connected with thecylinder at 0pposite sides of the piston and with a reversing valve. Thereversing valve is connected with the compressed air source forconnecting it with the conduits alternately in order to reciprocate thepiston. Means are provided for operating the reversing valve, preferablyfrom the compressed air in the system.

The preferred embodiment of the invention is illustrated schematicallyin the single figure of the a'ccornpanying drawing.

Referring to the drawing, it includes a reproduction of all of FIG. 1 ofthe drawings in Patent 3,225,544. The reproduced parts also have beengiven the same numbers as in the patent, but some of them will bedescribed more briefly herein. For a more detailed description, ifdesired, reference may be made to the patent. In the drawing of thisaplication, the bottom outlet of a hopper or bin 1 is shown closed by adoor or gate 2 that can slide in stationary tracks 3. For reciprocatingthe gate in order to open and close it, one end of it is pivotallyconnected by a link 4 to the upper end of a lever 5, the lower end ofwhich is pivotally connected to the outer end of a piston rod 6 attachedto a piston 7 in a fluid pressure cylinder 8. The lever is pivotallyconnected to a suitable support 9. It will be seen that when the pistonis moved to the left-hand end of the cylinder the link and lever willpull the gate away from the bottom of the bin to open its outlet. Whenthe piston is returned to the right-hand end of the cylinder, the gatewill be closed.-

For accomplishing these movements of the piston in the cylinder, a pipe11 is (onnected to the right-hand end or gate-closed end of thecylinder, while another pipe 12 is connected to the opposite orgate-open end of the'cylinder. These pipes may be flexible in Whole orin part if desired. Both pipes terminate at control means forselectively connecting a source of compressed air with either of themand for connecting the other pipe with the atmosphere. Such means mayinclude a conventional fluid pressure operated valve 13 having asolenoid- .actuated pilot. As shown, the valve connects pipe 11 with theatmosphere and simultaneously connecting pipe 12 with a line 18 leadingfrom a source of compressed air, such as a compressor 19. When thecontrol valve is reversed, it connects the compressor with pipe 11 andconnects pipe 12 with the atmosphere. Thus, by operating .this valve,air pressure can be delivered to either end of cylinder 8 in order tomove the piston therein back and forth. The apparatus described thus faris satisfactory as long asthe necessary air pressure is maintainedin'line 18.

However, if while the gate is open, the air pressure in the systemshould happen to drop below the amount necessary to close the gate,thirty pounds per square inch absolute for example, emergency apparatuswill come into operation automatically to move piston 7 towards thegate-closed end of the cylinder. Accordingly, pipe 12 is provided with afirst valve 23 that normally is closed by a closure member 25. However,the valve contains fluid pressure responsive means for opening it, whichmay be a plunger 26 slidably mounted in the bottom of the valve, whichopens into the upper end of a tube 29 connected with compressed air line18. As soon as pressure in the line is built up to a predeterminedpoint, it will force the plunger upward and thereby open the valve asshown so that compressed air can flow through pipe 12 to cylinder 8 whencontrol valve 13 .is in the position shown. When the control valve isreversed, air from the cylinder will escape through valve 23 and thecontrol valve to the atmosphere. As long as the gate-operating apparatusis in use, and functioning properly, valve '23 will remain open;

Also connected with the compressed air line -18 is a. reservoir 31,which is charged with compressed air from the compressor. This reservoiris connected by a conduit 32 with pipe 12 between valve 23 and cylinder8. This conduit contains a second valve 33 that normally is held open bya coil spring 34 pressing the movable closure member 35 away from itsseat. This valve likewise contains fluid pressure responsive means,which may be in the form of a plunger 37 in the bottom of the valve. Thebottom of the valve is connected by a tube 40 to compressed air line 18,so that While the compressor is opertion of this apparatus, valve 23 isheld open and valve 33 is held closed by the compressed air delivered bythe compressor through line 18 and tubes 29 and 40. However, in casethere is a failure of pressure while the gate is open so that it cannotbe closed in the normal ,way by compressed air flowing through valve 23,the drop in pressure below a predetermined value will permit the valve23 to close and valve 33 to open. The moment valve 23 is opened,compressed air in the reservoir is connected through conduit 32 and pipe12 with the left-hand end of the operating cylinder to drive piston 7toward the opposite end of the cylinder and close the gate. After thediffieulty that reduced the air pressure has been corrected so that theproper pressure can be built up in the system again, the air from thecompressor Will reopen valve 23, close valve 33 and recharge thereservoir through check valve 41. The reservoir is then ready to operatethe piston again if another emergency should ever arise.

Obviously, the capacity of the reservoir should be great enough toprovide sufiicient air pressure to force the piston toward thegate-closed end of the cylinder and hold it there. To ensure havingsufficient pressure for this purpose, and yet not provide a reservoirthat is larger than it needs to be, the proper size for the reservoircan be determined in advance. It can be determined by multiplying theair pressure .per square inch absolute in the charged reservoir by thevolume of the reservoir, and dividing the product by the combined volumeof the reservoir and cylinder. The result will be the air pressure persquare inch absolute available for shifting the piston in its cylinder.In this way a reservoir can be selected that will provide the desiredair pressure for operating the piston.

The apparatus described thus far is perfectly satisfactory for itsintended purpose, but in installations where cylinder 8 becomes quitelarge, reservoir 31 also would have to be made much larger, except forthis invention. Accordingly, it is a feature of this invention thatregardless of the size of cylinder 8, reservoir 31 can be maintainedquite small. This is accomplished by providing the apparatus with meansfor greatly augmenting the air pressure in the reservoir, such as by anintensifier 50 which is formed from two aligned cylinders containing twopistons. The upper cylinder 51 is shown considerably larger than thelower one 52, and therefore the .upper piston 53 is much larger than thelower piston 54. The two pistons are rigidly connected together by a rod55. The lower part of the small cylinder is supplied with compressed airthrough an extension 57 of compressed air line 18. This pipe is providedwith a check valve 58 that opens toward the intensifier. The same partof the intensifier is connected by a discharge pipe 59, containing acheck valve 60, with the reservoir 31.

To move the upper piston 53 up and down in its cylinder in order toreciprocate the lower piston and thereby force air under high pressurethrough pipe 59 into the reservoir, a conduit 62 is connected to theupper end of .uppr cylinder '51 and another conduit 63 is connected tothe lower end of the cylinder. Both conduits lead to a reversing valve64 of the bi-sta-ble type, in which a pair of valve members 65 and 66are movable back and forth in chambers 67 and 68 by pistons 69 and 70and coil springs 71 and 72. When the valve members are held in theirleft-hand positions by the springs, as shown, a passage 73 connectsconduit 62 with the atmosphere by means of chamber 67 and a passage 74.At the same time, an inlet passage 75 from line 18, containing anormally open solenoid shutoff valve 76, is connected through chamber 68and a passage 77 with the lower conduit 63.

With the valves in the positions shown, air under pressure fromcompressor 19 is entering the bottom of the large cylinder of theintensifier and thereby forcing the piston therein to rise. When thereversing valve 64 is reversed, the lower conduit 63 is connected withexhaust through chamber 68 and a passage 78, and upper conduit 62 isconnected-with inlet passage 75 through chamber 67, so that air pressurefrom line 18 will be applied to the top of the upper piston 53 to forceit down in its cylinder. It .will thus be seen thatit the reversingvalve is reversed periodically, the pistons in the intensifier will bereciprocated by air from the compressor and some air from the compressorwill be increased in pressure by the intensifier and delivered to thereservoir. Consequently, the air in the reservoir can be maintained at amuch higher pressure than the compressor can supply, so that in anemergency there will be a sufiicient volume of compressed air to operategate cylinder 8 even though the reservoir is relatively small ascompared with the gate cylinder.

Another feature of this invention is that air from the compressor isused as the motive power for reversing the reversing valve 64. For thispurpose, the conduit 63 is connected by a branch pipe 80 to a pneumatictimer 81 that is connected to the left-hand end of the reversing valve.This timer permits air from the compressor to periodically move pistons69 and 70 and valve members 65 and 66 in the reversing valve to theright against the resistance of the coil springs pressing against them,whereupon the pistons in the intensifier 50 will be driven downwarduntil the timer allows the coil springs to return the valve member tothe left-hand position.

The timer may be formed from two timing valves 82 and 83 connected in.parallcLEach of these valves is provided with an orifice adjustable bya needle 84 to permit air to flow through the valve at a controlled slowrate. The two valves are connected at one end by a pipe 85 connected tobranch pipe 80, while their opposite ends are connected by a pipe 86that in turn is connected with a passage 87 in the reversing valveleading to the two pistons therein. Between passage 87 and timing valve82 there is a check valve 88. Between the other timing valve and pipe 80there is another check valve 89. One of these check valves opens towardthe reversing valve and the other one opens away from it.

It will be seen that while compressed air is entering the bottom of thelarge cylinder 51 of the intensifier, it also is flowing slowly throughpipes 80 and 85 and timing valve 82 and into the adjacent end of thereversing valve. At about the time the pistons in the intensifier reachthe tops of their cylinders, the air pressure against the pistons in thereversing valve becomes great enough to unbalance the valve memberstherein and shift them to the right, thereby connecting the compressorwith the top of the intensifier and connecting the bottom of the largepiston 53 with exhaust. Of course, at the same time the timer isconnected with exhaust through pipe 80, As the air pressure against thereversing valve pistons slowly discharges through timing valve 83 toexhaust, the intensifier pistons are being moved downward to increasethe pressure of the air in reservoir 31. At about the time they reachthe lower ends of their cylinders, the air pressure in the reversingvalve has been reduced to such a point that springs 71 and 72 can expandand quickly push valve members 65 and 66 back to their originalpositions, wherein the compressor again will be connected with conduit63 and the timer, while the upper conduit 62 will be connected withexhaust. This automatic periodic reversal of the reversing valvetherefore causes the intensifier to operate like a pump and increase theair pressure in the reservoir.

When the pressure in the reservoir reaches the desired level, provisionis made for shutting 01? the intensifier. This may be done by connectingthe solenoid coil 90 of the shutolf valve 76 with a normally-open fluidpressure switch 91 responsive to the air pressure in the reservoir. Whenthat pressure rises to the desired value, it will move the diaphragm 92in the pressure switch to the left and thereby cause a bridging bar 93to span the electric contacts 94 so that the circuit to the shutoffvalve will be closed. This will cause the valve member 95 in that valveto be moved to the right in order to shut oif flow of compressed air tothe upper cylinder 51 of the intensifier. Whenever the pressure in thereservoir drops, due to leakage or to use of the air therein, pressureswitch 91 will open again and that will allow the shutoif valve to openso that the intensifier can start operating again to build the pressurein the reservoir back up to the desired level.

It will be observed that the intensifier is operated entirelyautomatically by the same compressor that charges the compressed airreservoir, and that the only additional power required is theelectricity used for closing shutoif valve 76, when the pressure in thereservoir is at its maximum.

According to the provisions of the patent statutes, I have explained theprinciple of my invention and have illustrated and described what I nowconsider to represent its best embodiment. However, I desire to have itunderstood that, within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically illustrated anddescribed.

I claim:

1. In fail-safe gate-operating apparatus having a reservoir containingcompressed air that is used only for closing a gate in emergencies, anda source of compressed air for charging the reservoir, of a pressureintensifier connected with said reservoir for increasing the airpressure in the reservoir above the pressure supplied by said source,said intensifier including a cylinder containing a piston for operatingthe intensifier, a pair of conduits connected with the cylinder atopposite sides of the piston, a reversing valve connected with saidsource for connecting it with said conduits alternately to reciprocatethe piston, and means for operating the valve.

2. In fail-safe gate-operating apparatus according to claim 1, saidvalve connecting one conduit with the atmosphere when it connects theother with said source, and said valve-operating means including aspring urging the valve in one direction and an air line permanentlyconnected with one of said conduits to employ the pressure from saidsource for moving the valve in the opposite direction.

3. In fail-safe gate-operating apparatus according to claim 2, saidfluid pressure line containing a timer comprising an air passageprovided with a restricted orifice and a check valve opening toward thereversing valve, and a second air passage provided with a restrictedorifice and a check valve opening away from the reversing valve.

4. In fail-safe gate-operating apparatus according to claim 1, saidintensifier receiving compressed air from said source, increasing itspressure and delivering it to the reservoir.

5. In fail-safe gate-operating apparatus according to claim 1, anormally-open valve connecting said source with said reversing valve,and means controlled by the pressure in said reservoir for closing saidnormally-open valve when that pressure rises to a predetermined value.

6. In fail-safe gate-operating apparatus according to claim 5, saidnormally-open valve being electrically operable, and saidpressure-controlled means being a normally-open pressure switchelectrically connected with said normally-open valve and closable by apredetermined pressure in said reservoir.

7. In fail-safe gate-operating apparatus according to claim 1, a conduitconnecting said source with the intensifier for delivering compressedair thereto to be increased in pressure thereby and delivered to thereservoir,

a normally-open electrically operated valve connecting said source withsaid reversing valve, said pressure-controlled means being anormally-open pressure switch electrically connected with saidnormally-open valve and closable by a predetermined pressure in saidreservoir, said reversing valve connecting one of said pair of conduitswith the atmosphere when it connects the other with said source, andsaid valve-operating means including a spring urging the reversing valvein one direction and an air line permanently connected with one of saidpair of conduits to employ the pressure from said source for moving thereversing valve in the opposite direction and containing a pneumatictimer.

8. Fail-safe gate-operating apparatus comprising a fluid pressurecylinder, a piston therein, a piston rod attached to the piston andextending out of one end of the cylinder for opening and closing a gate,pipes connected to the opposite ends of the cylinder, a source ofcompressed air, control means for selectively connecting said sourcewith either of said pipes and connecting the other pipe with theatmosphere to move the piston from one end of the cylinder to the other,a normally closed first valve in the pipe that delivers compressed airto the end of the cylinder from which the piston moves to close thegate, said valve containing fluid pressure responsive means for openingit, means for delivering compressed air from said source to saidpressure responsive means to hold the valve open during normal operationof the apparatus, a reservoir, a conduit connecting the reservoir withsaid valved pipe between said valve and cylinder, a normally-open secondvalve in said conduit provided with fluid pressure responsive means forclosing it, means for delivering compressed air from said source to thepressure responsive means of the second valve to hold that valve closedduring normal operation of the apparatus, a conduit connecting saidsource of compressed air with the reservoir, a check valve in saidlast-mentioned conduit permitting flow of air therethrough only towardthe reservoir to charge it with compressed air, a pressure intensifierconnected with said reservoir for increasing the air pressure in thereservoir above the pressure supplied by said source, said intensifierincluding a cylinder containing a piston for operating the intensifier,a pair of conduits connected with the cylinder at opposite sides of thepiston, a reversing valve connected with said source for connecting itwith said pair of conduits alternately to reciprocate the piston, andmeans for operating the reversing valve.

9. Fail-safe gate-operating apparatus according to claim 8, including ashut oil valve normally connecting said source with said reversingvalve, and means controlled by the pressure in said reservoir forclosing said shut-01f valve when that pressure reaches a predeterminedmaximum.

No references cited.

EDGAR W. GEOGHEGAN, Primary Examiner.

1. IN FAIL-SAFE GATE-OPERATING APPARATUS HAVING A RESERVOIR CONTAININGCOMPRESSED AIR THAT IS USED ONLY FOR CLOSING A GATE IN EMERGENCIES, ANDA SOURCE OF COMPRESSED AIR FOR CHARGING THE RESERVOIR, OF A PRESSUREINTENSIFIER CONNECTED WITH SAID RESERVOIR FOR INCREASING THE AIRPRESSURE IN THE RESERVOIR INCLUDING A CYLINDER CONBY SAID SOURCE, SAIDINTENSIFIER INCLUDING A CYLINDER CONTAINING A PISTON FOR OPERATING THEINTENSIFIER, A PAIR OF CONDUITS CONNECTED WITH THE CYLINDER AT OPPOSITESIDES OF THE PISTON, A REVERSING VALVE CONNECTED WITH SAID SOURCE FORCONNECTING IT WITH SAID CONDUITS ALTERNATELY TO RECIPROCATE THE PISTON,AND MEANS FOR OPERATING THE VALVE.